false advertising

I placed an order from KFC via Uber eats and it was showing that if I buy one meal I will get the other for free but I'll pay for the delivery my oder came cold after long period of waiting and it was cold and not complete the other meal was not there only one meal was delivered, I then ask the guy to give me the receipt and KFC said there is not receipt I must used the one on uber eats app and when I ask the delivery guy for the meal he also doesn't seem to know what say or what order was he suppose to deliver. so I am very disappointed with KFC together with Uber eats they are not making our lives easier instead they are making them difficult with the false advertising that they currently running In partnership so KFC and Uber eat please advise where does the other meal comes from on the buy one and get one free add